>>>>>> This is expected behavior. It's how the concatenate Python function manages to handle axis=None to flatten the arrays before concatenation. This has been in NumPy since 1.0 and should not be changed without deprecation warnings which I am -0 on.
>>>> Now, it is true that the C-API could have been written differently (I think this is what Mark was trying to encourage) so that there are two C-API functions and they are dispatched separately from the array_concatenate method depending on whether or not a None is passed in. But, the behavior is documented and has been for a long time.
>>>> Reference PyArray_AxisConverter (which turns a "None" Python argument into an axis=MAX_DIMS). This is consistent behavior throughout the C-API.
>> How about something like:
>> #define NPY_NONE_AXIS NPY_MAXDIMS
>> to make it clearer what is intended?
+1
-Travis